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2nd to neutral = cut out

maldotcom2

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Cammed mafless VS Calais 5-speed.
I've got a VS which i just converted to manual, it generally drives fine. But when i'm slowing down at the lights and i downshift through the gears to 2nd, then as i hit the clutch and pull it into neutral it'll cut out as i brake to a stop. Not like a normal stall, but the revs just fall to zero. If i pull it into neutral from 3rd or above and brake to a stop it's fine.

I'm using a chip programmed for manual, it doesn't do this with an auto chip, but of course it has a constant engine light.
 

maldotcom2

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Cammed mafless VS Calais 5-speed.
Anyone got a theory?

I've revised the problem, it's basically 2nd or 3rd into neutral, the revs will just gradually drop to zero as i slow down, UNLESS i blip the throttle when in neutral before it would cutout. Doing this causes the engine to splutter a bit like it's running rich, but it won't cut out.

It's also throwing an engine light after say 10 minutes of driving, not after any particular action but just driving along. I'm yet to get an error code out of it though.
 

hako

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Maybe the IAC sticky as that should correct the idle to stop it stalling.....maybe it's overfuelling as you go down thru the gears when in theory there should be no fuel going to the injectors...what about the MAF fouled with oil if you run a K&N airfilter.
 

muttley383

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Are you still running the auto pcm?
I would say that you have not got the correct speed signal going to the pcm.
 

maldotcom2

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Cammed mafless VS Calais 5-speed.
All the auto stuff is still there (auto computer if thats what you mean), and it ran fine with the auto memcal/eprom but it threw an engine light. So this is undesirable.

I put in a memcal/eprom designed to turn off the "oh **** no auto box" error codes, and it did, but now i have this problem. After a short distance it throws an engine light too, but when i check for codes i just get code 12.

Worth getting a new IAC?
 

hako

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Don't clean the IAC with anything that leaves a residue....carby cleaner is fine and make sure no crud gets into the plunger when cleaning/spraying. Petrol can also be used but takes a bit longer. Also check the distance between the tip of the pintle and the flange - it must be no more than 28mm.
 

muttley383

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How did you allow for the different type of speed input signals from auto to manual transmissions?
The 2 wire auto speed sender unit outputs an inductive pulse at 10x the frequency of the manual 3 wire trans hall effect sender unit. If nothing was done other than wiring changes then I would say that your computer is not registering any road speed input.
If no road speed is realised then this is the reason for the engine stalling when coming to a halt.
 

delcowizzid

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its fead into the second input for VSS on the ecu theres a pin for both types of sensor
 
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